Electronic transport and vibrational modes in the smallest molecular bridge: H2 in Pt nanocontacts

TL;DR

This paper uses first-principles calculations to analyze electronic transport in platinum nanocontacts with hydrogen, challenging previous interpretations by suggesting dissociated hydrogen complexes are responsible for observed conductance features.

Contribution

It provides a new interpretation of conductance peaks in Pt-H2 nanocontacts, proposing dissociated hydrogen complexes rather than molecular H2 as the main contributor.

Findings

Main conductance peak is due to Pt2H2 complex, not molecular H2.

Vibrational analysis aligns with experimental data supporting the dissociation hypothesis.

Identifies two forms of hydrogen-involving bridges during contact breaking.

Abstract

We present a state-of-the-art first-principles analysis of electronic transport in a Pt nanocontact in the presence of H2 which has been recently reported by Smit et al. in Nature 419, 906 (2002). Our results indicate that at the last stages of the breaking of the Pt nanocontact two basic forms of bridge involving H can appear. Our claim is, in contrast to Smit et al.'s, that the main conductance histogram peak at G approx 2e^2/h is not due to molecular H2, but to a complex Pt2H2 where the H2 molecule dissociates. A first-principles vibrational analysis that compares favorably with the experimental one also supports our claim .